Institute of Multidisciplinary Research for Advanced Materials, Tohoku University


LAST UPDATE 2023/08/04

  • 研究者氏名
    Researcher Name

    石上啓介 Keisuke ISHIGAMI
    助教 Assistant professor
  • 所属
    Professional Affiliation

    Institute of Multidisciplinary Research for Advanced Materials, Tohoku University

    無機材料研究部門 ナノスケール磁気機能研究分野
    Division of Inorganic Material Research, Nanoscale Magnetism
  • 研究キーワード
    Research Keywords

    Hard Ferromagnetic Material
    Permanent Magnet
    Bayesian statistics
    Machine Learning
Research Subject
Understanding the external field response of permanent magnet materials using Bayesian statistics and machine learning

研究の背景 Background


It is of industrial and social importance to identify the key factor and to clarify the mechanism for improving the magnetic properties of Nd-Fe-B sintered magnets, which are widely used as one of the permanent magnet materials for achieving a carbon-neutral and low-energy society. Since the beginning of its development, it has been known that the magnetic properties of Nd-Fe-B sintered magnets can be improved by doping heavy rare earth elements and controlling the microstructure by post-sinter annealing, but the mechanism is not well understood.

研究の目標 Outcome


In this study, to identify the latent factor contributing to the enhancement of magnetic properties of permanent magnetic materials and to understand the mechanism, we will utilize experimental science (synchrotron radiation X-ray diffraction and spectroscopy), computational science (physics-based simulation), and data science (Bayesian statistics and machine learning). This study will contribute to the effective and rational design of magnetic properties of new permanent magnetic materials.

研究図Research Figure

Fig.1. The purpose of this study is to identify the phase transformation associated with coercivity enhancement during post-sinter annealing of Ga-containing Nd-Fe-B sintered magnets by supervised learning based on sparse modeling of the coercivity with the in-situ X-ray diffraction pattern and to rank the importance of the identified phase transformations [1].

Fig.2. Sparse modeling of the coercivity by the X-ray diffraction pattern shows that the generation of the Nd6Fe13Ga phase and the annihilation of the dhcp-Nd phase correlate positively with the coercivity enhancement, while the presence of NdO correlates negatively. The former has been pointed out in previous studies, while the latter is newly revealed in this study.

文献 / Publications

[1] K. Ishigami et al., “Understanding the Coercivity of Ga-containing Nd–Fe–B Sintered Magnets from Feature Extraction and Selection of X-ray Diffraction Patterns via Dimension Reduction and Sparse Modeling”, INTERMAG 2023, Accepted for publication.